Search (7 results, page 1 of 1)

  • × theme_ss:"Retrievalalgorithmen"
  • × author_ss:"Willett, P."
  1. Perry, R.; Willett, P.: ¬A revies of the use of inverted files for best match searching in information retrieval systems (1983) 0.00
    0.00334869 = product of:
      0.00669738 = sum of:
        0.00669738 = product of:
          0.01339476 = sum of:
            0.01339476 = weight(_text_:a in 2701) [ClassicSimilarity], result of:
              0.01339476 = score(doc=2701,freq=4.0), product of:
                0.053105544 = queryWeight, product of:
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.046056706 = queryNorm
                0.25222903 = fieldWeight in 2701, product of:
                  2.0 = tf(freq=4.0), with freq of:
                    4.0 = termFreq=4.0
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.109375 = fieldNorm(doc=2701)
          0.5 = coord(1/2)
      0.5 = coord(1/2)
    
    Type
    a
  2. Al-Hawamdeh, S.; Smith, G.; Willett, P.; Vere, R. de: Using nearest-neighbour searching techniques to access full-text documents (1991) 0.00
    0.0030255679 = product of:
      0.0060511357 = sum of:
        0.0060511357 = product of:
          0.012102271 = sum of:
            0.012102271 = weight(_text_:a in 2300) [ClassicSimilarity], result of:
              0.012102271 = score(doc=2300,freq=10.0), product of:
                0.053105544 = queryWeight, product of:
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.046056706 = queryNorm
                0.22789092 = fieldWeight in 2300, product of:
                  3.1622777 = tf(freq=10.0), with freq of:
                    10.0 = termFreq=10.0
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.0625 = fieldNorm(doc=2300)
          0.5 = coord(1/2)
      0.5 = coord(1/2)
    
    Abstract
    Summarises the results to date of a continuing programme of research at Sheffield Univ. to investigate the use of nearest-neighbour retrieval algorithms for full text searching. Given a natural language query statement, the research methods result in a ranking of the paragraphs comprising a full text document in order of decreasing similarity with the query, where the similarity for each paragraph is determined by the number of keyword stems that it has in common with the query
    Type
    a
  3. Robertson, M.; Willett, P.: ¬An upperbound to the performance of ranked output searching : optimal weighting of query terms using a genetic algorithms (1996) 0.00
    0.0030255679 = product of:
      0.0060511357 = sum of:
        0.0060511357 = product of:
          0.012102271 = sum of:
            0.012102271 = weight(_text_:a in 6977) [ClassicSimilarity], result of:
              0.012102271 = score(doc=6977,freq=10.0), product of:
                0.053105544 = queryWeight, product of:
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.046056706 = queryNorm
                0.22789092 = fieldWeight in 6977, product of:
                  3.1622777 = tf(freq=10.0), with freq of:
                    10.0 = termFreq=10.0
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.0625 = fieldNorm(doc=6977)
          0.5 = coord(1/2)
      0.5 = coord(1/2)
    
    Abstract
    Describes the development of a genetic algorithm (GA) for the assignment of weights to query terms in a ranked output document retrieval system. The GA involves a fitness function that is based on full relevance information, and the rankings resulting from the use of these weights are compared with the Robertson-Sparck Jones F4 retrospective relevance weight
    Type
    a
  4. Li, J.; Willett, P.: ArticleRank : a PageRank-based alternative to numbers of citations for analysing citation networks (2009) 0.00
    0.0025370158 = product of:
      0.0050740317 = sum of:
        0.0050740317 = product of:
          0.010148063 = sum of:
            0.010148063 = weight(_text_:a in 751) [ClassicSimilarity], result of:
              0.010148063 = score(doc=751,freq=18.0), product of:
                0.053105544 = queryWeight, product of:
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.046056706 = queryNorm
                0.19109234 = fieldWeight in 751, product of:
                  4.2426405 = tf(freq=18.0), with freq of:
                    18.0 = termFreq=18.0
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.0390625 = fieldNorm(doc=751)
          0.5 = coord(1/2)
      0.5 = coord(1/2)
    
    Abstract
    Purpose - The purpose of this paper is to suggest an alternative to the widely used Times Cited criterion for analysing citation networks. The approach involves taking account of the natures of the papers that cite a given paper, so as to differentiate between papers that attract the same number of citations. Design/methodology/approach - ArticleRank is an algorithm that has been derived from Google's PageRank algorithm to measure the influence of journal articles. ArticleRank is applied to two datasets - a citation network based on an early paper on webometrics, and a self-citation network based on the 19 most cited papers in the Journal of Documentation - using citation data taken from the Web of Knowledge database. Findings - ArticleRank values provide a different ranking of a set of papers from that provided by the corresponding Times Cited values, and overcomes the inability of the latter to differentiate between papers with the same numbers of citations. The difference in rankings between Times Cited and ArticleRank is greatest for the most heavily cited articles in a dataset. Originality/value - This is a novel application of the PageRank algorithm.
    Type
    a
  5. Jones, G.; Robertson, A.M.; Willett, P.: ¬An introduction to genetic algorithms and to their use in information retrieval (1994) 0.00
    0.0023435948 = product of:
      0.0046871896 = sum of:
        0.0046871896 = product of:
          0.009374379 = sum of:
            0.009374379 = weight(_text_:a in 7415) [ClassicSimilarity], result of:
              0.009374379 = score(doc=7415,freq=6.0), product of:
                0.053105544 = queryWeight, product of:
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.046056706 = queryNorm
                0.17652355 = fieldWeight in 7415, product of:
                  2.4494898 = tf(freq=6.0), with freq of:
                    6.0 = termFreq=6.0
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.0625 = fieldNorm(doc=7415)
          0.5 = coord(1/2)
      0.5 = coord(1/2)
    
    Abstract
    This paper provides an introduction to genetic algorithms, a new approach to the investigation of computationally-intensive problems that may be insoluble using conventional, deterministic approaches. A genetic algorithm takes an initial set of possible starting solutions and then iteratively improves theses solutions using operators that are analogous to those involved in Darwinian evolution. The approach is illusrated by reference to several problems in information retrieval
    Type
    a
  6. Willett, P.: Best-match text retrieval (1993) 0.00
    0.0016913437 = product of:
      0.0033826875 = sum of:
        0.0033826875 = product of:
          0.006765375 = sum of:
            0.006765375 = weight(_text_:a in 7818) [ClassicSimilarity], result of:
              0.006765375 = score(doc=7818,freq=2.0), product of:
                0.053105544 = queryWeight, product of:
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.046056706 = queryNorm
                0.12739488 = fieldWeight in 7818, product of:
                  1.4142135 = tf(freq=2.0), with freq of:
                    2.0 = termFreq=2.0
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.078125 = fieldNorm(doc=7818)
          0.5 = coord(1/2)
      0.5 = coord(1/2)
    
    Type
    a
  7. Robertson, A.M.; Willett, P.: Use of genetic algorithms in information retrieval (1995) 0.00
    0.001353075 = product of:
      0.00270615 = sum of:
        0.00270615 = product of:
          0.0054123 = sum of:
            0.0054123 = weight(_text_:a in 2418) [ClassicSimilarity], result of:
              0.0054123 = score(doc=2418,freq=2.0), product of:
                0.053105544 = queryWeight, product of:
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.046056706 = queryNorm
                0.10191591 = fieldWeight in 2418, product of:
                  1.4142135 = tf(freq=2.0), with freq of:
                    2.0 = termFreq=2.0
                  1.153047 = idf(docFreq=37942, maxDocs=44218)
                  0.0625 = fieldNorm(doc=2418)
          0.5 = coord(1/2)
      0.5 = coord(1/2)
    
    Abstract
    Reviews the basic techniques involving genetic algorithms and their application to 2 problems in information retrieval: the generation of equifrequent groups of index terms; and the identification of optimal query and term weights. The algorithm developed for the generation of equifrequent groupings proved to be effective in operation, achieving results comparable with those obtained using a good deterministic algorithm. The algorithm developed for the identification of optimal query and term weighting involves fitness function that is based on full relevance information